Incremental drive mechanisms

ABSTRACT

A tape incrementing mechanism comprises a wire wrapped around a drum and coupled to a shaft carrying a tape drive sprocket through a one-way clutch device in combination with a piston and a lever for pulling the wire in one direction to rotate the shaft in one direction and so increment the tape the distance moved by the tape being accurately controlled by a stop cam co-operating with the levers to stop the shaft and sprocket after a predetermined angular movement thereof and a spring for pulling the wire back in the opposite direction without movement of the sprocket due to the interposition of the one-way clutch device.

United States Patent Gwillim et al.

[54] INCREMENTAL DRIVE MECHANISMS [72] Inventors: David Thomas Gwillim, Bransgore; Robin Joseph Whiting, Broadstone,

both of England [73] Assignee: Plessey Handel Und Investments A.G., Zug, Switzerland [22] Filed: Feb.24, 1971 21 Appl. No.: 118,335

[30] Foreign Application Priority Data Feb 25, 1970 Great Britain ..9,l43/7O [52] US. Cl ..226/156 [51] Int. Cl. ..B65h 17/22 [58] Field of Search.... ..226/156, 1 57, M8, 134

[S6] References Cited UNITED STATES PATENTS 3,145,892 8/1964 Hermann ..226/156 X 51 Oct. 24, 1972 3,292,832 12/1966 Drillick ..226/l48X Primary Examiner-Richard A. Schacher Attorney-Blum, Moscovitz, Friedman & Kaplan [57] ABSTRACT A tape incrementing mechanism comprises a wire wrapped around a drum and coupled to a shaft carrying a tape drive sprocket through a one-way clutch device in combination with a piston and a lever for pulling the wire in one direction to rotate the shaft in one direction and so increment the tape the distance moved by' the tape being accurately controlled by a stop cam co-operating with the levers to stop the shaft and sprocket after a predetermined angular movement thereof and a spring for pulling the wire back in the opposite direction without movement of the sprocket due to the interposition of the one-way clutch device.

5 Claims, 5 Drawing Figures PATENTED um 24 I972 SHEET 2 0r 3 mechanisms for punched tape and the like and is especially applicable to the incrementing of punched tape in pneumatic tape readers.

According to the invention as broadly conceived a tape incrementing mechanism comprises a wire or similar element wrapped around a drum and coupled to a shaft carrying a tape drive sprocket through a oneway clutch device in combination with means operable for pulling the wire in one direction to rotate the shaft in one direction to increment the tape, the distance moved by the tape being accurately controlled by means effective to stop the shaft and sprocket after a predetermined angular movement thereof, and means for pulling the wire back in the opposite direction without movement of the sprocket due to the interposition of the one-way clutch device.

The means operable for pulling the wire in said one direction may comprise an air piston acting on a pivoted lever while the means for arresting the sprocket shaft may comprise a system of levers including said pivoted lever co-operating with a suitably profiled cam fast on the sprocket-carrying shaft.

, According to a more specific feature of the present invention there isprovided a tape incrementing mechanism comprising two pivoted levers one of which is arranged to be actuated in response to the operation of an air piston out of locking engagement with a stop cam coupled to a shaft carrying a drive sprocket for the tape, the actuation of said one lever resulting in the shaft and thus the drive sprocket being rotated in response to the rotation of a drum, coupled to the shaft through a one-way clutch, by the displacement of a wire or the like wrapped around the drum and pulled at one end by the actuation of said one lever and acted on by tension spring means at the other end thereof, the other lever being moved about its pivot as the stop cam moves so that the other lever lockingly engages with the stop cam to arrest it and thus stop the drive sprocket when the cam has rotated through a predetermined angle of rotation and thereafter said one lever is returned to its unactuated position whereat it lockingly engages with the stop cam whereupon the other lever disengages from saidcam consequent upon the de-actuation of the air piston, and the wrapped wire is pulled back to its original position by the tension spring means. The drum being coupled to the sprocket shaft through a one-way clutch device is permitted to rotate with the sprocket in one direction while the clutch al lows independent rotation of the drum relative to the sprocket when the drum is rotated in the opposite direction.

The tape incrementing mechanism is especially suitable for use with pneumatic tape readers of the block reader type since the pressure air supply for the reader can be utilized for the actuation of the air piston of the incrementing mechanism in the more specific form of the mechanism described above. In the tape reader the punched tape to be read which passes over the drive sprocket of the incrementing mechanism may be arranged to be clamped against a tape reading face of a reader head having therein a multiplicity of holes corresponding to a block of possible positions for perforations in the tape and these holes may communicate with a common pressure chamber within the reader head. The clamping plate may have similarly positioned holes therein which are aligned with the reader head holes. Each block of perforations in the tape is read by feeding pressure air to all of the holes in the reading face and sensing the back pressures in the vicinity of the surface preferably through suitably positioned sensing pipes the input ends of which are set back from the reading surface within the corresponding holes. It will be appreciated that if a tape perforation is aligned with one of thereading face holes during a block reading operation then there will not be sufficient back pressure to produce a significant output from the pipe appertaining to the hole whereas a significant output will be derived from the pipe when the hole is blocked off by the tape.

By way of example the present invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic rear view of a punched tape incrementing mechanism according to the invention embodied in a punched tape reader of the block reader type; r

FIG. 2 is a view of the tape reader of FIG. 1 taken from the other side;

FIG. 3 is an end view of the tape reader taken in the direction K in FIG. 1;

FIG. 4 is a view showing the tape clamping device in association with the reader head; and,

FIG. 5 is a fragmentary view of the reader head showing the hole sensing pipe arrangement.

Referring to FIGS. 1 to 3 of the drawings the tape reader comprises a punched tape incrementing mechanism which includes a sprocket l which is fixedly coupled to a shaft 2 and over which passes punched tape 3 to be advanced by the mechanism in a step-bystep manner from one frame position to the next so that a different block of tape perforations is presented to a reader head 4 for reading purposes at each frame position of the tape 3. The sprocket shaft 2 has a drum 5 mounted on it and coupled to the shaft through a oneway clutch device 6 which allows rotation of the drum 5 independently of the shaft 2 in the counter-clockwise direction as viewed in FIG. 1. The sprocket shaft is also coupled to mounting panel 26 through a further oneway clutch device 43 (FIG. 3) which inhibits rotation of sprocket in reverse direction when other clutch is disengaged. For producing rotation of the drum and thus rotation of the sprocket l a wire 7 is wrapped around the drum 5, as can be seen in FIGS. 1 and 3, and this wire is anchored at one end to a coiled tension spring 8 and at its other end to a cylindrical nipple 9. The nipple 9 is held captive within a turned-over lower end part 10 of a spring strip 11 which normally bears against a stop or abutment member 12. The spring strip 11 is secured, as by rivets 13, to a lever 14 pivoted on pin 15. In the position of the lever 14 as illustrated a shoulder 16 on the lever engages in a notch 17 of a stop cam 18 which is fast on the shaft 2.

When incrementing of the punched tape is required pressure air is admitted to the cylinder of an air-piston cylinder device 19 to cause ram 20 to push against a nose 21 of the lever 14. The lever 14 moves about pivot 15 and as it does so it compresses the spring 11 and the shoulder 16 is withdrawn from the notch 17 of the cam 18. As the lever 14 moves, another lever 22, pivoted on pin 23 and having a pin 24 secured to it which is urged against the side of lever 14 by the action of a tension spring 25 anchored to the mounting panel 26 at 27, moves in the counter-clockwise direction as viewed in FIG. 1. It is arranged that the cam 18 starts to move in response to the pulling of the wire 7 by lever 14 when the bottom end of lever 14 engages the part of spring 11. This takes place before the bottom edge of the lever 22 engages with the periphery of the cam 18 and is held against the cam by the action of spring 25.

The cam 18, shaft 2 and sprocket 1 will continue to rotate as the lever 14 is forced outwards by the ram 20 until a notch 28 is engaged by the bottom end of lever 22 acted on by spring 25. At this stage the sprocket 1 will be arrested.

The punched tape will have been advanced by one frame corresponding to one block of tape perforations and will now be clamped by means to be described. The

pressure air will then be removed from the piston cylinder device 19 whereupon the drum 5 will be returned to its former position by the tension spring 8 pulling the wire 7 backwards, the one-way clutch device 6 permits the free return of the drum S'and the clutch device 43 prevents reverse rotation of sprocket. Spring 8, which is stronger than spring 11 which is stronger than spring 25, also returns the lever 14 to its original position and as the lever bears against the pin 24 during the return movement the lever 22 pivots in theclockwise direction (FIG. 1) so that it starts to be withdrawn from the notch 28 but the shoulder 16 of the lever 14 will engage the notch 28 before complete withdrawal of the lever 22 so as to hold the cam 18 securely in. the new position. The incrementing mechanism is now ready for the next operation to increment the tape to the next frame position. The punched tape 3 passes upwards between the reader head block 4 (FIG. 4) and a pneumatically actuated tape clamping device 29 which is actuated for clamping the punched tape between it and the perforated reading face of the reader block before reading of the tape takes place. The clamping device comprises a flexiblediaphragm 30 which carries a piston 31 for exerting clamping pressure on a perforated clamping block 32 when pressure-air is admitted to inlet port 33.

To retain the punched tape 3 in position over the sprocket 1 and to prevent undue lateral movement of the tape a hinged spring-urged tape guide and retaining member 34 is provided having a curved hood part 35 surrounding part of the sprocketand to facilitate insertion of the punched tape between the reader block 4 and clamping block 32 the member 34 may simply be pivoted in the clockwise direction about the hinge pin 36. A further tape guide member 37 is provided to guide the tape 3 as it leaves the sprocket 1.

It may here be mentioned that it is necessary to correctly position the blocks of perforations of the tapes with the reading face of the reader block 4 and for this purpose a pointer (not shown) is fitted over the tape feed sprocket which indicates the alignment of the tape with respect to the fifteenth frame. Moreover, the angular position of the sprocket l on its shaft 2 needs to be set with respect to the reader head 4. This is achieved by using a special gauge or a piece of tape and two screws in the sprocket. These two screws bear on a flat of the shaft 2 so that angular adjustment of the sprocket with respect to the shaft can be achieved.

Referring now to FIG. 5 of the drawings, this shows a fragment of the reader head. The head has a reading surface 38 which has a multiplicity of holes, such as the hole 39, therein. These holes all communicate with pressure chamber 40 to which pressure air is applied at a suitable input port (not shown). Each of the holes has a pipe, such as the pipe 41 arranged therein so that the input end of the pipe is set in from the reading face as illustrated. The arrangement is such that the tape clamping block 32 has holes, such as the hole 42, therein which are aligned with holes in the tape reading face. The punched tape-3 passes between the reader head 4 and the clamping block 32 and in the absence of a tape perforation a back pressure is developed in the pipe 41 and this may be used to effect operation of a fluidic relay at a remote location to indicate the absence of atape perforation. If a tape perforation is present no such back pressure is developed and thus no effective signal is derived from the pipe 41'. Consequently there would be no operation of the appertaining relay. The advantage of this technique is that when the tape has a hole the pressures in tube 41 falls slightly below theambient pressure, hence ensuring that diaphragm operated valves of the system are effectively switched off.

What we claim is:

1. A tape incrementing mechanism comprising an elongate element wrapped around a drum and coupled to a shaft carrying a tape drive sprocket through a oneway clutch device in combination with means operable for pulling the elongate element in one direction to rotate the shaft in one direction to increment the tape, the distance moved by the tape being accurately controlled by means effective to stop the shaft and sprocket after a predetermined angular movement thereof and means for pulling the elongate element back in the opposite direction without movement of the sprocket due to the interposition of the one-way clutch device.

2. A tape incrementing mechanism as claimed in claim 1, in which the means operable for pulling the elongate element in said one direction comprises an air piston acting on a pivoted lever while the means for arresting the sprocket shaft comprises a system of levers including said pivoted lever co-operating with a suitable profiled cam fast on the sprocket-carrying shaft.

3. A tape incrementing mechanism comprising two pivoted levers one of which is arranged to be actuated in response to the operation of an air piston out of locking engagement with a stop cam coupled to a shaft carrying a drive sprocket for the tape, the actuation of said one lever resulting in the shaft and thus the drive sprocket being rotated in response to the rotation of a drum, coupled to the shaft through a one-way clutch, by the displacement of an elongate element wrapped around the drum and pulled at one end by the actuation of said one lever and acted on by tension spring means at the other end thereof, the other lever being moved about its pivot as the stop cam moves so that the other lever lockingly engages with the stop cam to arrest it and thus stop the drive sprocket when the cam has rotated through a predetermined angle of rotation and thereafter said one lever is returned to its unactuated position whereat it lockingly engages with the stop cam whereupon the other lever disengages from said cam consequent upon the de-actuation of the air piston and the wrapped elongate element is pulled back to its original position by the tension spring means.

4. A tape reader including a tape incrementing mechanism as claimed in claim 4, in which the tape to be read passes over the drive sprocket of the incrementing mechanism and is arranged to be clamped against a tape reading face of a reader head having therein a multiplicity of holes corresponding to a block 

1. A tape incrementing mechanism comprising an elongate element wrapped around a drum and coupled to a shaft carrying a tape drive sprocket through a one-way clutch device in combination with means operable for pulling the elongate element in one direction to rotate the shaft in one direction to increment the tape, the distance moved by the tape being accurately controlled by means effective to stop the shaft and sprocket after a predetermined angular movement thereof and means for pulling the elongate element back in the opposite direction without movement of the sprocket due to the interposition of the one-way clutch device.
 2. A tape incrementing mechanism as claimed in claim 1, in which the means operable for pulling the elongate element in said one direction comprises an air piston acting on a pivoted lever while the means for arresting the sprocket shaft comprises a system of levers including said pivoted lever co-operating with a suitable profiled cam fast on the sprocket-carrying shaft.
 3. A tape incrementing mechanism comprising two pivoted levers one of which is arranged to be actuated in response to the operation of an air piston out of locking engagement with a stop cam coupled to a shaft carrying a drive sprocket for the tape, the actuation of said one lever resulting in the shaft and thus the drive sprocket being rotated in response to the rotation of a drum, coupled to the shaft through a one-way clutch, by the displacement of an elongate element wrapped around the drum and pulled at one end by the actuation of said one lever and acted on by tension spring means at the other end thereof, the other lever being moved about its pivot as the stop cam moves so that the other lever lockingly engages with the stop cam to arrest it and thus stop the drive sprocket when the cam has rotated through a predetermined angle of rotation and thereafter said one lever is returned to its unactuated position whereat it lockingly engages with the stop cam whereupon the other lever disengages from said cam consequent upon the de-actuation of the air piston and the wrapped elongate element is pulled back to its original position by the tension spring means.
 4. A tape reader including a tape incrementing mechanism as claimed in claim 4, in which the tape to be read passes over the drive sprocket of the incrementing mechanism and is arranged to be clamped against a tape reading face of a reader head having therein a multiplicity of holes corresponding to a block of possible positions for perforations in the tape and these holes communicate with a common pressure chamber within the reader head.
 5. A tape reader as claimed in claim 4, in which the clamping plate has holes similarly positioned to those in the tape reading face and are aligned therewith. 